As it is known, spinning mills or other similar machines of the spinning plants are fed with bobbin rows or trains, with a roving wound around the bobbins to feed the spinning mills. The bobbin trains are moved along a monorail, which extends in the plant following suitable paths.
In some cases, the bobbin trains are temporarily placed inside magazines formed by sections of the monorail, arranged in rows placed one above another.
When the bobbins of a row, or of a train, are exhausted, or, according to different substitution techniques, are getting exhausted, the whole row is removed from the section beside the spinning mill and carried toward the bobbins filling station, while a new row of previously filled bobbins, possibly taken from the magazine, is introduced into the empty section.
The number of the rows of bobbins, which are to be brought to each side of the spinning mill, depends substantially on the type of yarn to be obtained and on the method used for feeding the spinning mill, so as to reduce as much as possible, or to eliminate, the downtimes, during which the exhausted, or getting exhausted bobbins are substituted with the full supply bobbins.
For example, the Patent Application No. BO2001A 000750, filed by the Applicant, proposes a feeding system, in which the number of bobbin rows to be supplied is twice the number of rows necessary to obtain the desired yarn. This is due to the fact that each work bobbin row has its spare bobbin row.
Therefore, the number of bobbin rows on each side of the spinning mill can reach and be even higher than eight units.
The bobbin trains travel hung, by hooking means of known type, to the links of a chain, which slides inside the monorail. The monorail is formed by a box-like body with a cross-like section.
The box-like body is open above and below, so as to allow the driving means, placed at predetermined distances, to get in touch with a flat surface of the chain dragging the bobbin train.
This type of moving, the used chain and the motor means for this operation, are described in the Italian Patent No. 1.213.982.
Besides the pulling devices arranged along the path, which extends along the whole plant, there must be also another pulling device situated for each terminal section present beside the spinning mill, to move the bobbin train, when it is introduced into and removed from the section.
Taking into consideration the fact that one spinning plant includes some tens of spinning mills and that each spinning mill can feature, situated at each side thereof, even eight or more monorail sections which form the final, bobbin dwelling section, it is easy to calculate that some hundreds of pulling devices are necessary only for the terminal dwelling sections.
The same thing relates also to the dwelling sections which form the magazine, where the bobbin trains are temporarily placed before being sent toward the spinning mills or similar machines. Further waste of means is caused by the switch devices necessary for diverting the bobbin trains
from the main conveying line toward the desired terminal section of the spinning mills or of the magazine.
In order to understand the problem better, reference is made to FIG. 1a, which shows schematically a plant in its main parts.
The figure shows as an example only a part of the plant related to a spinning mill, and it is to be borne in mind that in case of a magazine, the plant configuration is substantially identical.
The numeral reference 3 indicates the main conveying line, along which the bobbin trains are conveyed from the spinning mills 1 to the bobbin roving frames, where the empty bobbins are substituted with the full bobbins, and then vice-versa from the magazine to the spinning mills, in order to substitute the bobbin trains getting exhausted.
Along the main path of the monorail 3, there are nodes 11, where the sections of the monorail curved toward the heads 2 of the spinning mills, branch off.
Switching devices 20 are situated in the conjunction areas 11.
Each switching device, having the configuration as shown in FIGS. 2a, 2b, 2c, includes a deviating plate 23, called “penna”, kept elastically in such a position as not to interfere with the path of the train along the main section 3.
When the path of the arriving train is to be changed toward a selected terminal section 10 or toward a dwelling section of a magazine, an activating device 25, formed usually by an electromagnetic or pneumatic activator. The activating device moves a lever, called also cam due to its cam profile aimed at avoiding possible jamming, and determines the rotation of the deviating plate, which interferes with the path of the bobbin train, thus directing it toward the branch arm 16.
As shown in FIG. 1a, each side of the spinning mill is supposed to have three work bobbin rows and three spare bobbin rows. Thus, the total number of the terminal sections 10 will be twelve units.
Therefore, at the present state, twelve pulling devices 31 are needed.
The figure shows in the most complete way only the first of the terminal sections 10, however it is understood that the other terminal sections have the same configuration. The main path 3 extends gradually toward the terminal sections 10.
First, three branch arms 16 extend from the main path 3 and then each branch arm 16 is divided, thus obtaining six segments 16, 17 which are further divided obtaining twelve conjunction sections 16, 17, 18, which join with the twelve terminal sections 10.
Otherwise, the twelve conjunction segments 16, which join the main line 3 with the twelve terminal sections 10 can be used, as shown in FIG. 1b. 
In any case, only the spinning mill shown in FIGS. 1a and 1b needs a good twelve devices activating the deviating plate 23 of twelve switches, which multiplied by the number of spinning mills determine the use of some hundreds of activators, each equipped with a relative feeding and control circuit.
The same conditions are valid for the magazine.
The high number of the devices pulling bobbin trains and devices operating the switches determines a cost increase which, if already high in small or medium plants, assumes remarkable levels for the valuation of the manufacturing costs in a big plant with hundreds of spinning mills.